When there are changes of owners or temporary occupants in buildings (apartments, shops, etc.), it is necessary to invalidate the old keys for the locks and to validate new ones.
The valid coding of a key is established by sets of slots that operate between the barrel and the tube of the combination cylinder, so that it is possible to modify the opening code (and, therefore, the valid key necessary) without the necessity of having to substitute the remainder of the cylinder and the lock. Nevertheless, for this, it is necessary to extract the cylinder of the lock, which requires a slow and costly labor for demounting and remounting from this lock.
In order to carry out the extraction of the cylinder without having to disassemble the rest of the lock, a system is known that consists of making a special cylinder that can be extracted by means of a special master key that operates under the power of professional locksmiths and upon which has been copied the code of the user's key of this lock.
One important problem in this system is that it requires making up a special basic and costly assembly, i.e., the combination cylinder. This adversely affects standardization in the production and marketing of the product. Moreover, it cannot be applied in traditional locks that are lacking such a special cylinder.